This invention relates generally to pivot joints, and in particular to a disengageable pivot joint particularly useful for connecting a headlamp adjuster to the reflector inside a headlamp assembly. It also can be used as a compact disengageable connector that allows pivotable movement within the attachment. The improved ball socket, while particularly useful in connection with a disengageable ball stud such as the ones described herein, can also be effectively used in connection with conventional ball studs.
Pivotable spherical joints, commonly referred to as ball joints, include a ball stud engaged in a socket. Such joints have a wide variety of applications where a pivotable connection between two parts is desirable. For example, they may be used in many types of linear actuators and have been found to be particularly useful in automotive lamp assemblies. As shown in FIG. 17, similar to FIG. 2 of U.S. Pat. No. 5,707,133 incorporated herein by reference, automotive lamp assemblies 200 used as headlights typically comprise several basic parts: a support frame 202, a reflector 204, a lens 206, a bulb (not shown), and one or more adjusters 210. The support frame 202 houses the reflector 204 and the bulb on a pivotable mounting to allow the aim of the light to be adjusted using the adjuster 210. The lens 206 seals the front of the assembly 200 to protect it from the elements assailing the front end of the vehicle and provides an aerodynamic shape and attractive appearance. In such an automotive lamp assembly 200, the reflector 204 mounts inside the housing on one fixed ball joint 212 and is adjustable horizontally and vertically using adjusters 210 that interface with the reflector 204 through moving ball joints 214. The moving ball joints 214 are moveable by actuating the adjusters 210 connected to the moving ball joints 214 by a ball stud having a head and a shaft. Ball joints are required because of the many possible adjustments that may be made to the orientation of the reflector 204. If ball joints are not used, the reflector 204 into which the adjusters 210 are fitted will not be properly adjustable because the reflector 204 will not be positionable in both the vertical and horizontal directions. Right angle adjusters are typically used to allow the adjustment of the headlight from an adjusting position above the installed headlight. In other applications, a motorized adjuster, a straight adjuster, or another type of adjuster is used.
In some adjusters, the ball stud rotates upon actuation of the adjuster unless it is prevented from doing so by engaging tabs ("ears") or similar structure on the ball stud. Such adjusters are not readily adaptable for use with the present disengageable ball stud invention but may be used in connection with an embodiment of the improved ball socket invention. Examples of such adjusters are disclosed in U.S. Pat. Nos. 4,689,725, 5,161,877 and 5,186,531 and an example of an "eared" ball stud is shown in FIGS. 24 and 24A. Adjusters for use with the present disengageable ball stud invention should have a means for preventing rotation of the ball stud, head, and shaft included in the adjuster. For example, the adjuster disclosed in U.S. Pat. No. 5,707,133, incorporated herein by reference, is ideally suited for use with the present invention as it uses an anti-rotation insert that engages grooves on the shaft to prevent rotation of the ball stud. While one possible application of the present invention is in headlamp assemblies, other applications are possible and references to use in a headlamp assembly should not be deemed to limit the possible uses of the present invention. Additionally, while the improved ball socket design described herein is ideally suited for use with a disengageable ball stud, such as the ones described herein, it can also be used advantageously with conventional ball studs including those with "ears" or engaging tabs.
As shown in FIGS. 1, 2A, and 2B, conventional ball joints for use in automotive lamp assemblies typically include a ball stud 20 with a spherical engagement head 22 extending from an adjuster, the ball stud 20 is capable of being moved linearly in and out of the adjuster (arrows 24 and 26). Such conventional ball studs 20 typically interface with a plastic socket 28 attached to the reflector such that movement of the ball stud effectuates movement of the reflector. The interface between the ball stud 20 and the socket 28 is such that the head 22 of the ball stud 20 cannot be readily removed from the socket 28 once the head 22 is secured therein. This is because of fingers or tabs 30 protruding from the opening of the socket 28 that retain the head 22 in the socket 28. The fingers or tabs 30 have relief areas 32 interposed therebetween. Retention in the socket is desired because the bead 22 cannot be allowed to slip from the socket 28 once the adjuster is installed or the adjuster will not be able to adjust of the orientation of the reflector. When engaged in the socket 28, the head 22 of the ball stud 20 is free to pivot within the cup portion 33 of the socket 28.
Additional examples of prior art ball stud and corresponding sockets are shown in FIGS. 4 and 5 of U.S. Pat. No. 4,689,725, FIG. 2 of U.S. Pat. No. 5,161,877, FIG. 1 of U.S. Pat. No. 5,673,992, FIG. 2 of U.S. Pat. No. 5,095, 411, and FIGS. 10-14 of U.S. Pat. No. 5,186,532. Additionally, several U.S. patents are directed toward ball joints for use in headlamp adjusting mechanisms: U.S. Pat. Nos. 4,974,123, 5,047,904, and 5,063,481.
While functionally quite effective, there is a major drawback to using conventional ball joints and sockets in modern sealed automotive lamp assemblies. The relatively permanent installation of conventional ball stud heads into sockets does not allow removal of the ball stud should the lamp assembly or adjuster need to be replaced. In conventional assemblies, if the lamp assembly or the adjuster is found to be defective, the entire assembly, including the adjuster, is usually discarded or completely disassembled and reworked. Discarding an entire assembly or an entire adjuster can be quite expensive and it is desirable to salvage the properly working parts, especially in cases where the adjuster is an expensive motorized version.
Typically, a "peanut style" socket, such as the one shown in FIGS. 1, 2A, and 2B, is used in connection with ball studs in headlamp adjusters. While somewhat effective, and capable of being used with either the disengageable ball stud described herein or a conventional ball stud, there are several drawbacks to using a "peanut style" ball socket. For example, such sockets require multiple parts on the assembly line--the plastic socket piece and the screw. This requires multiple part numbers and an additional step (matching the screw to the socket piece) in the assembly process. Additionally, in such sockets, the point of attachment to the reflector--the screw--is relatively distant from the socket--the place where the stress is imparted on the pieces. This allows deflection of the piece between the attachment and the socket which may result in inconsistent aiming performance. Furthermore, such sockets require a relatively large boss on the reflector in order the properly attach the socket and mount the ball stud thereon.
Accordingly, a need exists for a ball joint that is easily assembled, wherein the head of the ball stud is removable if desired but retains its engagement in the socket as required, maintains its pivotability, cannot be removed from the socket unless desired, and is cost-effective. Additionally, the need exists for an improved ball socket that is easily installed in the lamp, securely retains a ball stud placed therein, can be effectively used in connection with disengageable or conventional ball studs, and is cost effective. The present invention relates to an improved ball joint which is capable of being used in automotive lamp assemblies and solves the problems raised or not solved by existing ball joints. Of course, the present invention may be used in a multitude of non-automotive lamp situations where similar performance capabilities are required.